blowing fuses,aftermarket guages?

Bumping this thread as I have an Autometer coolant/temp gauge that I think is pooched. Its an Autometer #2635. After 1 minute of engine running it reads over 250(pegged)but actual temp is nowhere near that hot (verified with temp gun).
This problem started last year after thermostat failed and car overheated. I replaced sender last year after overheating and gauge still pegs.

Any idea how to test/chk coolant temp gauge?

Thanks
Steve